578 



UicHAN'co (L. B.). Reproduction in the Aphididae, with a Consideration 

 of the modifying Influence of Environmental Factors. — Psyche, 

 Boston, Mass., xxviii, no. 4, August 1921, pp. 95-109. TReceived 

 3rd October 1921.] 



Parthenogenesis in Aphids is apparently continuous under favour- 

 able conditions, and it has practically supplanted amphigony, in which 

 both sexes are concerned. The latter occurs only under the influence 

 of low temperatures, and according to some authors, as the result of an 

 inadequate food-supply. If the quantity of food has any influence 

 at all on the determination of amphigony in a parthenogenetic mother, 

 the effect does not become manifest in the immediate offspring. In 

 certain species the amphigonous generation continues to occur at 

 definite cyclical intervals for some time after the influence of low 

 temperature has been eliminated. In colder climates Aphids undergo 

 a change in the method of reproduction as an adaptation to adverse 

 environmental conditions, but the relation of food to this phenomenon 

 is not definitely known. 



Departmental Activities : Entomology. — .//. Dept. Agric. Union S. 

 Africa, Pretoria, iii, no. 3, September 1921, pp. 208-210. 



Attention is again drawn to the permits that are necessary in respect 

 of importations of cotton seed. Permits are onty given for seed to be 

 sown, and then only to the extent of 10 lb. of a variety to any one 

 applicant. The importance of these restrictions has been indicated 

 several times in the past year by the finding of the pink bollworm 

 [Platyedra gossypiella] in small parcels of North African seed, and, 

 during the past month, by the presence of a few dead adults of the 

 Mexican boll weevil ( Anthonomus grandis) in a parcel of seed from the 

 United States. 



Aloes in Pretoria have been damaged for several seasons by the 

 weevils, Brachycerus inter stitialis, Fhs., and B. monachus, Fhs. Their 

 life-histories have not been fully worked out ; they appear to lay 

 eggs in the crown of the aloe plant, and the larvae descend the leaves 

 into the stem. If the terminal bud is injured, the plant may die and 

 rot away. The adults also eat out irregular patches of the leaves. 

 A smaller species, Mecistocerus aloes, Mshl., occurs in numbers in the 

 crown of the plant, where the adults gnaw out circular cavities in the 

 young leaves, leaving only the surface membrane. All three species 

 are very difficult to deal with owing to the protected habitat of the 

 larvae ; the only effective measures seem to be the cutting out of the 

 grubs from infested plants and hand-collection of the adult beetles. 



Plum-trees in Pretoria and various other localities in the Transvaal 

 are frequently defoliated by the caterpillars of Parasa latistriga ; other 

 cultivated plants are attacked and sometimes oak trees. The oval cases 

 in which they hibernate and eventually pupate are easily found, and 

 crushing them is often the simplest way of destroying the insect. 



M.\LLV (C. W.). Insect Pests. A Factor in Green Manuring. — 



//. Dept. Agric. Union S. Africa, Pretoria, iii, no. 3, September 

 1921, pp. 219-224, 4 figs. 



Green manuring is an excellent method of improving the condition 

 of the soil, but is unfortunately frequently followed by invasions 

 of insect pests which may cause serious loss in fruit orchards or other 



